Excitation–ionization of the calcium atom by electron impact
Double differential cross sections, measured using an electron-photon coincidence method, are reported for the 4p 2P3/2 excited state of Ca+ produced by electron interaction with the 4s2 1S ground state of the calcium atom. The cross section at an incident electron energy of 400 eV is dominated by indirect processes involving 3p excitation to states lying 31.4-31.6 eV above the atomic ground state. These then autoionize to the observed 4p 2P3/2 ion state. Other indirect processes involving states with binding energies in the range 27-41 eV, including triply excited states, are also observed. Preliminary measurements of the linear Stokes parameters at the peak of the main resonance give P1 = -0.09 ᠰ.01 and P2 = 0.01 ᠰ.01.
Journal of Physics B: Atomic, Molecular and Optical Physics